This invention relates to frame relay, and more particularly to an arrangement for implementing frame relay in a network comprising, a plurality of nodes interconnected by communications circuits.
It is known to link Local Area Networks via multiplexers over, for example, T1 circuits. For example, Newbridge Networks Corporation MainStreet.RTM. 3600/45 multiplexers can be bridged to Ethernet LANs via Newbridge MainStreet.RTM. 8230 bridges. One of the major strengths of the Newbridge 4602 network management system is the rapid set-up of connections (or paths) through a network using a simple point-and-click paradigm. The end user selects the two endpoints and issues a "connect" request. The connect request causes the 4602 system to optimally route the call through the network using the physical resources available;
Underlying this concept is a database system that holds an abstraction of the objects making up the network (nodes, cards, ports, links, etc.) and a process (called the BandWidth Allocator, or BWA) that searches this abstraction for available, bandwidth and sends appropriate messages to real network elements to configure and connect the path. The supporting features in the 4602 system are well documented in the applicant's literature. In such a prior art configuration, however, the connection paths correspond to actual physical circuits.
Frame relay is a new and simplified packet switching technique specified in CCITT recommendations I.122 and Q.922, and ANSI documents T1.602 and T1.606, which allows for many paths to share the same physical bandwidth. End-to-end user paths are known as Frame Relay Paths (FRPs). Frame relay is designed to replace the older and theoretically slower X.25 service.
The manual set-up of an FRP is accomplished in a number of steps and is time-consuming and prone to error. At each network element (or node), the frame relay streams/backbones/pipes that overlay the physical network must be established. This overlay-network forms the highways that frames are allowed to ride on. This is accomplished using frame relay switch cards, which perform high speed frame relay switching. Frame stream circuits on these cards are cross-connected to physical network resources (e.g., data ports, primary rate timeslots, T1/E1 etc.). Cross connected to physical network resources are access ports to these services.
A locally unique address must be assigned to each endpoint of the frame relay path. These addresses are called DLCIs (Data Link Connection Identifiers). There may be many logical paths terminating at each access endpoint.
For each frame-relay path (FRP), the connectivity over the frame relay streams must be established by visiting each node and making appropriate local DLCI cross connects on the frame relay switches to allow frames to switch from one frame relay pipe to another. DLCIs are locally significant at each frame stream circuit only and may change at each switch along the way. Hence, there may be many DLCI cross-connects connects for each FRP. This set-up is very time consuming and must be done for each FRP. Since the DLCIs used at each switch must be locally unique on each frame stream and since there can be up to one thousand FRPs per frame stream, managing DLCI numbers becomes very difficult if done manually.